1 Building SPL/U-Boot for xea board
2 =================================
4 Setup environment, configure and build, e.g. by:
6 $ make imx28_xea_defconfig
7 $ make -j4 u-boot.sb u-boot.img
9 Now you should see u-boot.sb and u-boot.img files in the build directory.
15 The boot ROM loads SPL from SPI NOR flash into SRAM. SPL configures
16 DRAM and loads either a Linux kernel (falcon mode) or, if the rescue
17 pin is asserted, the main U-Boot. Both kernel and U-Boot reside in
18 eMMC boot partition 0. For redundancy, a copy of U-Boot is also
19 stored in SPI flash. If a valid kernel image is not found, U-Boot is
20 loaded from eMMC or, if this fails, SPI flash.
27 ------------------------------------------
28 0x00000000 SPL u-boot.sb
29 0x00010000 U-Boot u-boot.img
30 0x00080000 Environment
34 ------------------------------------------
35 0x00000000 U-Boot u-boot.img
36 0x00080000 Devicetree imx28-bttc.dtb
37 0x00100000 Kernel uImage
43 In falcon mode, the default, SPL loads the kernel and devicetree
44 directly. For this to work, the stored devicetree must include
45 correct "memory" and "chosen" nodes as these are not updated by SPL
46 before booting the kernel.
52 The default U-Boot environment includes command sequences to update
53 SPL, U-Boot, and kernel over TFTP. These are as follows:
55 - update_spl: writes u-boot.sb to SPI NOR
56 - update_uboot: writes u-boot.img to eMMC and SPI NOR
57 - update_kernel: writes kernel and devicetree to eMMC
59 They can be invoked at the U-Boot prompt using the "run" command,
60 e.g. "run update_spl" to update the SPL.
62 These update commands download the above-named files from the
63 ${hostname} directory on the server provided by DHCP.